Rubio, who placed second in South Carolina based on complete but unofficial returns, argued that his policy specifics trump Trump's big talk. "If you're running for president of the United States, you can't just tell people you're going to make America great again," Rubio said on CBS' "Face the Nation."

Cruz, right behind Rubio in the South Carolina vote, stressed his conservative credentials and said he was the lone "strong conservative in this race who can win. We see conservatives continuing to unite behind our campaign," he told NBC's "Meet the Press."

Trump, looking ever more in control of the race for the GOP nomination, opted against his trademark braggadocio in assessing the state of the race.

Asked on CBS if the race was his to lose, Trump said, "I don't want to say it's mine. Certainly I'm leading, there's no question about that, but we've got a long way to go."

The GOP candidates were fanning out Sunday to Nevada, Tennessee, Arkansas, Georgia and beyond as the race spreads out and speeds up after the kickoff trio of Iowa, New Hampshire and South Carolina. Nevada's GOP caucuses are Tuesday, and then a dozen states vote in the March 1 Super Tuesday bonanza.

The Democrats next compete Saturday in South Carolina after Hillary Clinton blunted concerns about her viability with a clear victory over Bernie Sanders in Nevada, the first state to test the Democrats' appeal among a racially diverse group of voters.

Clinton celebrated her Nevada triumph but acknowledged she has work to do in persuading voters that she has their best interests at heart.

"I think there's an underlying question that maybe is really in the back of people's minds and that is, you know, is she in it for us or is she in it for herself?" Clinton said on CNN's "State of the Union." ''I think that is a question that people are trying to sort through."

Sanders took a hard look at the where the delegate math takes him from here. He acknowledged that while he has made gains on Clinton, "at the end of the day ... you need delegates." He looked past South Carolina and ticked off Colorado, Minnesota, Massachusetts and Oklahoma as places where he hopes to do well.

Trump, now the clear leader in the delegate race, cemented his standing as his party's favorite. No Republican in modern times has won New Hampshire and South Carolina and then failed to win the nomination.

Trump's victory was vindication for political mavericks whose hunger for an outsider has defined this year's campaign. But those fortunes didn't extend to Sanders this weekend. After winning the second contest in New Hampshire, the democratic socialist came up in short in Nevada, where Clinton collected the majority of delegates and told gleeful supporters that "this one is for you."

For Republican Jeb Bush, it was the end of the line. With donors ready to bolt, the political scion dropped out of the race after failing to break into the top three.

A string of victories for Clinton and Trump in Super Tuesday contests would give them commanding leads in the delegate race, dampening prospects for their rivals to catch up. Already, Trump leads Republicans with 67 of the needed 1,237 delegates, with Cruz at 11 and Rubio at 10. Clinton has 503 to Sanders' 70, including party officials known as superdelegates who back the candidate of their choice.

The biggest question facing Republicans now is whether those seeking to spoil a Trump nomination have simply run out of time.

Rubio and Cruz argued that with roughly 70 percent of GOP voters consistently voting for someone other than Trump, they have an opening as the GOP field keeps shrinking.

Rubio called it the "alternative-to-Donald-Trump vote," and predicted it would coalesce around him.

Cruz countered that he's the only Republican who's been able to beat Trump so far, referring to his victory in leadoff Iowa.